Comments on: Virtualization platforms http://blogs.hds.com/hu/2006/02/virtualization_.html Hu Yoshida, VP and CTO of Hitachi Data Systems, provides his insight into industry issues, discusses in his own words storage best practices, and provides realistic solutions to real storage problems of current and next generation storage environments. Thu, 21 Aug 2008 19:40:00 +0000 http://wordpress.org/?v=2.0.4 by: Hu Yoshida http://blogs.hds.com/hu/2006/02/virtualization_.html#comment-170 Mon, 27 Feb 2006 15:35:33 +0000 http://blogs.hds.com/hu/2006/02/virtualization_.html#comment-170 Hello Nathan, you are right. It is the architecture, and it must be designed for the application. The thing to remember is that nothing stands still. As applications or business requirements change and morph, hardware and software will need to change so I doubt that either will ever be commoditized. Hello Nathan, you are right. It is the architecture, and it must be designed for the application. The thing to remember is that nothing stands still. As applications or business requirements change and morph, hardware and software will need to change so I doubt that either will ever be commoditized.

]]> by: Hu Yoshida http://blogs.hds.com/hu/2006/02/virtualization_.html#comment-169 Mon, 27 Feb 2006 15:26:43 +0000 http://blogs.hds.com/hu/2006/02/virtualization_.html#comment-169 Alex, thanks for reading my blog and taking the time to send your comments. I stand corrected. An SVC consists of 2 nodes each of which have 4 ports so an SVC cluster has 8 ports. And you are right you can cluster 8 of these together and get 64 ports, some number of which connect to servers and some number connect to storage. What if you need to connect thousands of hosts and peta bytes of storage? I don't think that provides the scalability you need for a virtualization solution. Its been some time since I looked at the SVC, so I may be out of date. If you need to do a code upgrade to the SVC clusters can you do it non disruptively? Storage is all about not losing data. Call me old fashion, but if there is a write to volitile memory, I say it must be mirrored for protection. That vendor you reffered to must agree since he added mirror cache to his latest announcement. Alex, thanks for reading my blog and taking the time to send your comments.

I stand corrected. An SVC consists of 2 nodes each of which have 4 ports so an SVC cluster has 8 ports. And you are right you can cluster 8 of these together and get 64 ports, some number of which connect to servers and some number connect to storage. What if you need to connect thousands of hosts and peta bytes of storage? I don’t think that provides the scalability you need for a virtualization solution.

Its been some time since I looked at the SVC, so I may be out of date. If you need to do a code upgrade to the SVC clusters can you do it non disruptively?

Storage is all about not losing data. Call me old fashion, but if there is a write to volitile memory, I say it must be mirrored for protection. That vendor you reffered to must agree since he added mirror cache to his latest announcement.

]]> by: Nathan http://blogs.hds.com/hu/2006/02/virtualization_.html#comment-168 Tue, 14 Feb 2006 18:44:24 +0000 http://blogs.hds.com/hu/2006/02/virtualization_.html#comment-168 Hu, I think we need to go back first and say, the main goal is to design an architecture thats best for the specific application. Virtualization does mask complexity but masking technical complexity isn't just at the benfit of IT people. Your assessment on PC clustering is correct, hardware provides no resiliency and simple clustering isn't the solution either. The need is for smart software that is configured to handle hardware failures immediately and define the QoS of resources. Hardware doesn't make itself a commodity, the software that can run on it does. Nathan Hu,
I think we need to go back first and say, the main goal is to design an architecture thats best for the specific application.
Virtualization does mask complexity but masking technical complexity isn’t just at the benfit of IT people.
Your assessment on PC clustering is correct, hardware provides no resiliency and simple clustering isn’t the solution either.
The need is for smart software that is configured to handle hardware failures immediately and define the QoS of resources.

Hardware doesn’t make itself a commodity, the software that can run on it does.

Nathan

]]> by: Alex, MSc student, Edinburgh http://blogs.hds.com/hu/2006/02/virtualization_.html#comment-167 Sun, 12 Feb 2006 17:19:07 +0000 http://blogs.hds.com/hu/2006/02/virtualization_.html#comment-167 Hu, I must say that I really enjoy reading your blog. There are many interesting thoughts and observations posted here, but unfortunately sometimes they are mixed with pure marketing FUD. May I ask you to do one thing: could you please mark your marketing posts somehow, so that I could skip and not read them? I do understand that this is a corporate blog, and you must follow certain rules etc. But please, it's so obvious when you're trying to slay competitors simply because you have to. Have you ever though about running your own personal blog? -- "IBM SVC has only 4 ports, two for fan in and two for fan out." IBM San Volume Controller has 8 ports in minimal 2-node configuration and up to 32 ports in its maximum configuration. These ports are not dedicated to either fan-in or fan-out. In other words, same SVC ports are used for working with storage and hosts at the same time. "One application can dominate all the resources and starve the other applications of I/O resources." Each SVC-managed virtual disk can be configured with its own throttle rate specified either in IOPS or in MBps. This allows to allocate performance resources between different applications that use SVC. "You lose half your resources and you need maintenance windows to recover." When you cluster eight SVC nodes you would NOT need maintenance window to recover unless you lose all EIGHT of them. And let's not call them PC's because 1) These appliances are based on xSeries server platform which are a bit different to Dell Optiplex PC which I'm currently using to write this post. 2) There are several hardware modifications like independent hardware watchdog timer, custom FC HBA's, etc. SVC is NOT a PC. And I don't understand this thoughts expressed by "lone sysadmin" about clustering at all. The question whether to cluster or not could be asked 20 years ago or so (I'm a bit too young to tell for sure), nowdays everybody uses clustering. Show me a company that does not use clustering. Even the biggest machines are clustered these days, we all use redundant servers, fabrics etc. This is the simplest and the most affordable way to dramatically improve reliability of any system. "they need to update each other’s cache, since they do not share a global cache." I really like this one! The only reason SVC nodes need to update each other's cache is to mirror writes. We all know one hardware vendor who did not mirror cache in its arrays, but this is (surprisingly) not HDS! -- I'm not going to tell you why HDS approach is not the right one, you can ask {EMC, IBM, ...} sales people to do this job. I just admire this blog and I don't want to see lies here. Hu, I must say that I really enjoy reading your blog. There are many interesting thoughts and observations posted here, but unfortunately sometimes they are mixed with pure marketing FUD. May I ask you to do one thing: could you please mark your marketing posts somehow, so that I could skip and not read them? I do understand that this is a corporate blog, and you must follow certain rules etc. But please, it’s so obvious when you’re trying to slay competitors simply because you have to. Have you ever though about running your own personal blog?

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“IBM SVC has only 4 ports, two for fan in and two for fan out.”

IBM San Volume Controller has 8 ports in minimal 2-node configuration and up to 32 ports in its maximum configuration. These ports are not dedicated to either fan-in or fan-out. In other words, same SVC ports are used for working with storage and hosts at the same time.

“One application can dominate all the resources and starve the other applications of I/O resources.”

Each SVC-managed virtual disk can be configured with its own throttle rate specified either in IOPS or in MBps. This allows to allocate performance resources between different applications that use SVC.

“You lose half your resources and you need maintenance windows to recover.”

When you cluster eight SVC nodes you would NOT need maintenance window to recover unless you lose all EIGHT of them. And let’s not call them PC’s because
1) These appliances are based on xSeries server platform which are a bit different to Dell Optiplex PC which I’m currently using to write this post.
2) There are several hardware modifications like independent hardware watchdog timer, custom FC HBA’s, etc. SVC is NOT a PC.

And I don’t understand this thoughts expressed by “lone sysadmin” about clustering at all. The question whether to cluster or not could be asked 20 years ago or so (I’m a bit too young to tell for sure), nowdays everybody uses clustering. Show me a company that does not use clustering. Even the biggest machines are clustered these days, we all use redundant servers, fabrics etc. This is the simplest and the most affordable way to dramatically improve reliability of any system.

“they need to update each other’s cache, since they do not share a global cache.”

I really like this one! The only reason SVC nodes need to update each other’s cache is to mirror writes. We all know one hardware vendor who did not mirror cache in its arrays, but this is (surprisingly) not HDS!

–

I’m not going to tell you why HDS approach is not the right one, you can ask {EMC, IBM, …} sales people to do this job. I just admire this blog and I don’t want to see lies here.

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